Unifying optical gain and electro-optical dynamics in Er-doped thin-film lithium niobate platform

Modulation and amplification are two fundamental processes in optoelectronics. While discrete implementations have achieved widespread success, the challenge of monolithically integrating sufficient gain and electro-optic bandwidth remains a significant barrier, limiting optical systems’ miniaturization and scalability. We unify these two functions in the Er-doped thin-film lithium niobate (Er:TFLN) platform, achieving a record-high internal net gain of 38 dB in a 9.16-cm-long waveguide amplifier. Meanwhile, leveraging the host material’s strong Pockels effect, we realize ultra wide-range electro-optic modulation with a bandwidth of 53 GHz and operation up to 170 GHz, fabricated alongside waveguide amplifiers using a zero-change process. Additionally, we validate this functional fusion through two signal processing scenarios: self-amplified digital signal encoding and pre-amplified broadband radio frequency front-end receiving, demonstrating improved signal recovery quality compared to off-chip gain. The modulation-amplification integration holds broad potential for increasing system complexity and network depth in applications such as optical interconnections, Lidar, and microwave photonics. By unifying ultra-high optical gain and broadband electro-optic dynamics in an Er-doped lithium niobate thin-film platform, the authors demonstrate an exciting monolithic integration of amplification and modulation on a compact photonic chip. This exciting work showcases record performance for on-chip amplifiers while enabling self-amplified 50 Gbps digital encoding and pre-amplified RF front-end signal recovery.